Here is the full list of all 25 MazM: The Phantom of the Opera achievements.
Get Carlotta's help when in a slump.
Face Carlotta's punishment after she finds out the truth.
On the first payday, face humiliation while trying to show authority.
Lie to Erik, which won't work.
Give the Mask to Erik.
Reject the train ticket.
Take the train ticket.
Acquired footnote
Give the Mask to Melek.
Force Meg with an order again.
Find out the truth about the flaming head.
Believe in the one you love, risking your life.
Meet Meg Giry, Sorelli, and Jammes with Christine
Reveal the identity of the horrifying man.
Destroy the 'masterpiece' on purpose, to infuriate someone.
After meeting the Angel, find singing skills have improved.
Witness the 'Phantom of the Opera' at the farewell party.
Find out what the kitty is thinking.